Process of producing diformin.



UNITED STATES PATENT oEEIcE.

SIGMUND VON KAPFF, OF BOXGRABEN-AAOHEN, GERMANY.

PROCESS OF PRODUCING DIFORMIN'.

Specification of Letters Patent.

Patented Oct. 13, 1908.

Application filed December 23, 1907. Serial No. 107,833.

To all whom it may concern:

Be it known that I, SIGMUND Von. KAPFF, a subject of the King of Wiirtemberg, residing at 100, Boxgraben-Aachen, Germany,

have invented certain new and useful Immins with lycerin, t. 6. products wlich are not perfect y soluble in ether, whereas pure formins dissolve colorlessly in ether. In the case of the known troublesome and, according to the statement of Beilstein, difficult method diformin could therefore only beob tained pure b digesting the reaction mass with ether. he cause of the incomplete formation of formin lies in the absence of a suitable condensing agent. All condensing agents known hitherto convert glycerin into acrolein. Now it has been found that anhydrous or concentrated formic acid as condensing agent yields no acrolein when formin is formed, but takes up the water of condensation, so that the formic acid which is left over for the reaction converts the glycerin at once and completely into formin, i. e. forms diformin when the necessary quantit is em-- ployed.\ This condensation takes place exceedingl rapidly; simultaneously it is possible to istil off the water, which is liberated during the condensation, as well as the formic acid which is used as condensi agent, so that-only ure formin remains be ind as the product 0 the reaction in the distilling ap aratus. This employment of formic am is new and forms the essential element of the patent claim.

Exam le: 1 kg. 100 formic acid is mixed with 0,4 concentrated (say 95%) glycerin and heated. At 100 C. and over dilute formic acid at once commences to be distilled away. The distillation is continued until the temperature has risen to about 140 0., when diformin remains behind.

The reaction of the process will be understood from the following equation 1- ragon zncoon formic acid C H OH (COOH) 2 2H O) diformin I While the concentration of the gl cerin employed is stated to be 95%, it is to eunderstood that the process may be successfully carried out with glycerin of greater or less strength than this.

Other formins than formic acid glycerin ester, for example ethylene-diforrnin and erythrite-.tetraformiate, are also obtained by boiling with concentrated formic acid, but in this case long continued boiling with very glycerin considerable excess of formic acid is necessary in order to gain the desired end. Thus this is not an analogous process, all the less as glycerin also otherwise behaves essentiall differently from glycol and erythrite.

at I claim as my invention and desire to secure by Letters Patent is:

1. A method of producing diformin consisting in subjecting glycerin to the direct action of formic acid in the presence of a large excess of formic acid, to act as a condensing agent and in distilling away formic acid and water.

2. In the process ofproducing diformin, the subjection of glycerin to the direct action of formic acid in the presence of a large excess of formic acid to act as a condensing agent, substantiall as described.

In testimony w iereof I have 'signed my name to this specification, in the presence of two subscribing witnesses.

SIGMUND VON KAPFF.

Witnesses:

HENRY QUADFLIEG, 'ELIsE KALBUSCH. 

